Mass determination of masonry, surcharge for cut-off

He said according to VOB doors and windows under 2.5 sqm are not deducted.

The additional effort compared to "bricklaying through" to place these gaps cleanly at very specific points is only offset by the saved material with larger gaps. I consider this a practically fair solution to also represent this flat-rate in the calculation.

With Excel it's just a few clicks.

With bricklaying, the stop-and-go is a bit more awkward.

There was no tender. I went to the general contractor and gave him the floor plan as I envisioned it, and after a few appointments he created an offer.

If you approached a GC, why are you interested in his quantity calculation? You sign a fixed price, don't you? Then the only thing that matters to you is the final amount. You then compare that with the next offer.